reel
A device consisting of radial arms with horizontal stats, connected with a harvesting machine, for holding the stalks of grain in position to be cut by the knives.
reel: rotating arm that feeds grain into the cutter
A reel is the rotating assembly mounted on the front of a grain combine or binder that gathers standing stalks and feeds them toward the cutting mechanism. It consists of four or more radial arms extending from a central hub, with horizontal tines or slats spaced along each arm. As the machine moves forward, the reel rotates backward, combing the crop inward and downward to lay it against the cutting bar or knife where the stalks are severed.
The reel works in tight coordination with ground speed and forward motion. Harvest quality depends on getting the reel speed and positioning exactly right: too fast and the reel tosses grain ahead of the cutterbar; too slow and stems bend rather than cut cleanly, or lodged grain fails to feed through. Most combines use a variable-speed reel, either belt-driven or hydraulic, allowing the operator to adjust rotation speed independently of ground speed. Older binders typically had a fixed reel speed geared directly to the main driveshaft.
Reel diameter typically ranges from 4 to 5 feet, and the number of tines per arm varies with crop and design, usually between 6 and 12. A wider reel gathers a broader swath of standing grain. Wheat and barley reels differ slightly from those designed for oats or more delicate crops. Some reels have straight arms; others use slightly curved arms to improve the combing action and reduce grain shatter as material enters the cutterbar.
Common problems include bent or broken tines from striking stones or stubble, which causes uneven feeding and lodged stems. Tine wear gradually reduces the grip on crop, so operators must inspect and replace damaged tines regularly. Improper reel height causes either cutting above the grain head or dragging through soil. Misalignment between reel speed and ground speed is the leading cause of slugging, where the cutterbar becomes choked with partially fed stems.
The reel's name reflects its function: it reels the standing crop toward the cutting mechanism, much as a fishing reel winds in line. In older literature it appears as the "header reaper reel" to distinguish it from the spring-loaded gathering chains used on some swathing machines. The term reel is universal across English-speaking grain regions, though tractor operators sometimes call it the "gathering reel" or simply "the gathering mechanism."